Method of forming artificial vascular members



July 4, 1961 P. DEMSYK" METHOD OF FORMING ARTIFICIAL VASCULAR MEMBERS Filed Jan. 30, 1957 United welm 2,990,605 METHOD OF FORMING ARTIFICIAL VASCULAR MEMBERS Paul Demsyk, 576 E. 25th St., Paterson, NJ. Filed Jan. 30, 1957, Ser. No. 637,287

Claims. (Cl. 28 76) .1 1

This invention relates to a method of forming artificial vascular members for implantation'in an animal body, including the body of the human species.

More particularly it relates to sectionsof blood vessels formed artificially of'textile material assuming the form of tubing when distended by blood or other fluid flowing therethrough. V i l One of the principal features of the present invention is that it affords a section of textiletubing which does not nearly or completely collapse when no fluid pressure is applied to the inside thereof, but which remains distended to a very substantial extent when empty.

Textile tubing for implants has hitherto been usually woven upon a loom, for example a loom of the type termed in the textile art Jacquard. The materials employed have usually been the synthetic textiles such as nylon and ethylene glycol te'rephthalic acid polyester (Dacron). Such tubes usually are 12. to 18 inches in length and appear to be two strips of flat tape, one superposed in parallel relation upon the other, and fastened to each other longitudinally alongboth edges or margins so that, up to the very moment when fluid pres sure is applied to the interior thereof, the two strips lie closely adjacent one another, i.e. the tube wallsassume a substantially completely collapsed state. This necessitates that some distention of thetubing be brought about by suitable physical manipulations, just prior to the implantation of the artifact within the biological organism, e.g. by applying super-atmospheric pressure of some fluid, such as air or blood, to the interior of the tubing. o v

The need for such physical manipulations is manifestly detrimental from the viewpoint of demanding precious time and distracting attention from the operative field at a highly critical moment. Likewise there always exists the risk of introducing foreign matter into the tubing, when such manipulations must be'restor-ted to, especially foreign matter which may prove later to have introduced pathogenic organisms into the vascular system, thereby often eventuating in unfortunate sequelae.

One object of this invention is to produce textile tubing for artificial vascular implants, which-tubing shall at all times remain open, or non-collapsed, to a substantial degree.

Another object of this invention is to avoid the necessity of a distending operation, prior to use, in connection with artificial vascular tubing.

A further object of this invention is to provide textile tubing which may assume the form of a Y or other junction shape and which remains open, so as to be ready for instant implantation.

With the above and other objects in view, as will hereinafter appear, the invention consists in the combination and arrangement of parts hereinafter set forth and illustrated in the accompanying drawings from which the several features of the invention and the advantages attained thereby will be readily understood by those skilled in the art.

Referring to the drawings wherein like reference characters designate like parts throughout the several views:

FIGURE 1 is a plan view of a section of implant tubing as first formed, before being subject to the treatment of this invention.

Patented July 4, 1961.

. 2 t FIGURE 2. is a cross sectional view on an enlatged scale, taken upon the line 2-2 of FIGURE 1. l

FIGURE 3 is a plan view of a tubinghaving inserted therein a forming tube. i FIGURE 4 is a sectional view, taken onthe line 4-4 OfFIGURE 3. j j FIGURE 5 is a diagrammatic view of a-steam chest, as used in this inventionrf e FIGURE dis a cross'sectional view ofafinished im planttubing. l FIGURE 7 is a cross sectional view of a modified form of implant tubing. 1 v a FIGURE 8 is a longitudinal section of a Y shaped implant, having formingtubes therein.

'Referring now to FIGURES l and 2, there is here shown a section of flattened tubing 5, havingselvage margins 6, 6; The appearance is that of two pieces of tape connected together in marginal fashion; From FIGURE 2, it is to be noted that the lumen which such tube must present, when carrying a stream of blood, is substantially completely blocked, instead of being inthe patent state which it is essential that it ultimately assume. The tubing material is preferably Dacron, as this presents the porosity which has been found to be a practical necessity in artificial implants, non-porous implants having usually failed to establishthemselves satisfactorily in a living organism, over an extended period of time.

Referring now to FIGURES 3 and 4, a tube or'rod 8 either hollow or solid, of relatively rigid material, such as metal or glass,of suitable diameter and length, is inserted within the Dacron tube 5, so as fully to distend the Dacron tube to a circular or oval cross section. Stainless steel has been found to be especially desirable as a material for this rigid tube. While a circular cross section is shown, an oval shaped rigid tube may also be employed.

Reference is now additionally made to FIGURE :5, which diagrammatically shows a steam chest 10, sometimes referred to as an autoclave. By dotted lines there is shown within this steam: chest the Dacron tubing 5 having therein the distending rigid tubing 8. It is to be understood that this steam chest will be supplied with the usual ancillary equipment adjuvant to the operation thereof, such as steam gauges, time indication and control means, superheated water vapor and steam supply, exhausts for conden'sed spent steam, and the like. The pressure in this steam chest is preferably not less than fifteen pounds and may go ashigh as twenty pounds.

The temperature found in the steam chest under such condition usually lies between 250? F. and 260 F. The length of treatment should be not less than ten minutes and may beextended up to a maximumof thirty minutes, beyond which time the results are less satisfactory. At the conclusion of the treatment, the usual procedure for'exhausting the steam under pressure takes place and the Dacron tubing together with the enclosed rigid tube 8, is removed from the steam chest. Upon removal of the rigid tube 8 from the Dacron tubing, the latter then assumes a form similar to that shown in FIGURE 6 of the drawings. In other words, it does not remain perfectly round, even though the rigid rod may have been round, but tends to assume an oval shape, with the margins 6 extending somewhat, in a plane at right angles to the shorter axis of the oval.

In FIGURE 7 there is shown an implant which is woven without the marginal portion 6. Such an implant tends to retain a closer approach to the round cross section of the rigid tube 8, when the latter has been removed therefrom.

Reference is now made to FIGURE 8 which shows one method of using this invention is order to construct an implant in the form of a junction. Such junction is usually in the form of a Y as shown in the drawings. The textile tubing is suitably woven and then a rigid tube orrod 20 is placed in the main line and two ancillary tubes 21, 21 are placed in the respective branch lines. The innermost ends of these rods may be shaped as shown in the drawings, so that they will substantially abut one another, without leaving any undue open space between the inner ends of the rods or tubes. 7 a

With this invention if sterilizing is necessary before implanting, the Dacron tube will hold the distended shape and form even though a rigid tube, rod or the like is not used at the elevated temperatures used in sterilizing.

Without further elaboration, the foregoing will so fully explain the invention that othersmay, by applying current knowledge, readily adapt the same for use under various conditions of service. Moreover, it is not indispensable that all the features of the invention be used conjointly since they may be employed advantageously in various combinations and subcombinations.

It is obvious that the invention is not confined solely to the use herein disclosed in connection therewith as it may be utilized for any purpose to which it is adaptable. It is therefore to be understood that the invention is not limited to the specific construction as illustrated and described, as the same is only illustrative of the principles involved which are capable of extended application in various forms, and the invention comprehends all construction within the scope of the appended claims.

What I claim is:

1. The method of forming an artificial vascular implant, consisting of the steps of forming a fabric tube consisting essentially of Dacron and which lies flattened and with collapsed walls when the internal and external pressures are equal, inserting within said fabric tube a rigid rod, having an external diameter only slightly less than the interior diameter of the fabric tube when the latter is distended, subjecting said tube and the rod held therewithin to a temperature of between about 250 F. and about 260 F. in an atmosphere composed chiefly of superheated water vapour and steam for at least ten minutes and not over thirty minutes, restoring said tube and rod to normal atmospheric temperatures and pressure, and removing said rod, whereby said fabric tube remains at least partly opened and with the walls thereof uncollapsed.

2. The method of forming an artificial vascular implant which will remain at least partly distended when the internal and external pressures are equal, consisting of the steps of forming a woven fabric tube consisting of Dacron and normally lying flat with the opposite walls in contact with one another, applying internal pressure to the walls of said tube, so that it assumes a substantially completely distended condition, subjecting the exterior wall of said tube to superheated water vapor and steam at between fifteen and twenty pounds pressure for between ten and thirty minutes, and removing the internal pressure from said tube, whereby the tube remains at least partly distended when no further pressure is applied to the interior thereof.

3. The method according to claim 2, wherein the external superheated water vapor and steam pressure is applied to the tube by temporarily confining the latter within a steam chest.

4. The method of forming an artificial vascular implant in the shape of a Y, consisting of the steps of forming a fabric tube in the shape of a Y, said tube consisting essentially of Dacron and the walls of said tube normally lying in a collapsed position, inserting in the main portion of the Y a relatively rigid rod and in each branch of the Y inserting another respective relatively rigid rod, the abutting ends of all three rods being so shaped as to meet one another without affording any substantial space therebetween, exposing the fabric tube containing said rods to superheated water vapor and steam pressure of from about fifteen to about twenty pounds for from about ten to about thirty minutes, and removing said rigid rods, whereby the Y shaped fabric tube so produced remains at least partly opened when subject to equal pressure within and without.

5. A method of making an artificial vascular implant consisting of forming a normally flat, woven, Dacron tube including two superposed fabric layers joined together at marginal portions of the tube, inserting a rod longitudinally through the space between said fabric layers to distend said normally fiat tube, subjecting the distended tube with the rod therein to an atmosphere comprising superheated water vapour and steam at about fifteen to twenty pounds pressure and 250 F. to 260 F. for between ten and thirty minutes, and then removing said rod from said tube, whereby the fabric layers of the woven Dacron tube will remain separated in the central portions thereof so that the tube will be partly open.

References Cited in the file of this patent UNITED STATES PATENTS 439,451 Ward Oct. 28, 1890 718,378 Painter Jan. 13, 1903 1,596,754 Moschelle Aug. 17, 1926 2,624,341 Wallace Jan. 6, 1953 2,836,181 Tapp May 27, 1958 2,845,959 Sidebotham Aug. 5, 1958 FOREIGN PATENTS 164,179 Australia July 18, 1955 744,735 Great Britain Feb. 15, 1956 OTHER REFERENCES Hufnagel: The Use of Rigid and Flexible Plastic Protheses for Arterial Replacement, Surgery, February 1955, vol. 37, No. 2, pages -174. (Copy in 128-1.)

Edwards and Tapp: Chemically Treated Nylon Tubes as Arterial Grafts, Surgery, July 1955, vol. 38, pages 61-70, publishers, C. V. Mosby Co., St. Louis, Mo. (Copy in Patent Ofiice Library and Division 21 Class 139, subclass 387.) 

